Process of carroting fur and compositions for carroting



solution containing mercuric nitrate, nitric Patented July 18, 1933CLARENCE 1.. WEIRICH, or wrs'rrom', conunc'rrcu'r PROCESS OF CA RROTINGFUR AND COMPOSITIONS FOR CARROTING No Drawing. Application filed May 21,

This invention relates to processes of carroting fur and compositionsfor carroting,- and it comprises a process wherein animal fur, forexample, rabbit fur is treated with a acid, and hydrogen peroxide, itfurther comprises processes wherein fur is treated with a carrotingsolution of the character just described to which a small amount of asoluble fluoride has been added, and it further comprlses a carrotingsolution containing mercuric nitrate, nitric acid, and hydrogenperoxide, to which a soluble fluoride is advantageously added.

Animal fur, such as that which goes to make upv an ordinary felt hat,must be processed to free it of dirt, coarse hairs, and waxy, perhaps'silicious, compounds which form a sort of coating about the hair fiber.Dirt and 0 coarse hairs can be easily removed from the fur by mechanicalmethods but the removal of the waxy coating requires chemical treatment.This coating obscures microscopic barb-like portions of the fiber and,before the fiber can be felted, it is necessary that the fiber be freedof the coating. A fiber which has been purified, and which is suitablefor felting, is one in which the coating has been removed so that thebarbs are exposed. These barbs play a prominent part in the feltingoperation.

The operation of treating the fur chemically to remove the outer coatingof waxy material is commonly referred to in the art as carroting. Anumber of different carroting solutions have been suggested. For a greatmany years, a solution of mercuric nitrate has been commonly employedand for some little understood reason, this substance is an effectivecarroting agent. Mercuric nitrate, however, possesses certaindisadvantages. Chief among them, as regards the character of thetreated. fur, is the fact that mercuric nitrate tends to give the fur ayellowish color.

drogenperoxide alone was sug ested a num r ofyears ago. In spite of tieclaims made for substitutes for mercuric nitrate, this substance stillremains the Of late, it has been proposed to 'use an alkaline solutionof hydrogen per oxide although h 1931. Serial No. 539,151.

best carroting compound at present known. One of the difficulties withusing alkaline solutions of hydrogen peroxide resides in the fact thatsuch solutions tend to decompose and it is desirable that a carrotingsolution be of such nature chemically that quantities of it can be kepton hand over moderately long periods of time.

I have now discovered that most of the disadvantages inherent in the useof mercuric nitrate solutions can be 'overcome provided hydrogenperoxide is added to the mercuric nitrate solution. Moreover, I havediscovered that the addition of a soluble fluoride enhances thecarroting action of a mercuric nitrate solution containing hydrogenperoxide.

y carroting solution accordinglycomprises an aqueous solution ofmercuric nitrate, free nitric acidand hydrogen peroxide to which isadded a small amount of a soluble fluoride.

My solution is advantageously prepared in the following manner. I firstmake up a mercuric nitrate solution by mixing 80 parts of a 40% nitricacid solution with 20 parts of metallic mercury. This gives me asolution containing about 32% of mercuric nitrate, 20% of free nitricacid and48% of water. This solution is about the same as the mer- .curicnitrate carroting solution ordinarily used. I

I then take one half gallon of the above solution, dilute it with threegallons of water and add thereto about one and one half gallons of watercontaining about'one half ounce of ammonium fluoride. To the resultingsolution I then add two and onehalf gallons of a commercial peroxideabout 3% strength) and finally two and one half gallons of water.

The above proportions are merely illustrative of my invention. Thequantity of hydrogen' peroxide can be varied within rather wide limits,say from one half gallon to four or five gallons and the amount ofammonium fluoride can be increased up to seven or eight ounces ifdesired. The quantity of fluoride depends largely upon the amount ofsiliceous material which must be removed from the fur fiber as morefully explained hereinafter.

The fur to be carroted is then treated with Eli solution (usually I thethus prepared solution until the carroting carroting compounds to attackthe waxy action has proceeded to the desired extent. underlying coating.

I find that fur carroted with my solution Although I have stated what Ibelieve to does not develop the yellow color ordinarily be the action ofthe various substances in my 5 observed when mercuric nitrate is usedalone. solution, I nevertheless do not wish to be I attribute this tothe presence of the hydrobound by the theory proposed. The above genperoxide in the carroting solution. explanation is, however,areasonableone and Probably the peroxide acts as a bleaching I believe itapproximates the true state of afagent to destroy any color which mightotherfairs. It will thus be apparent that, as stated, wise result.Moreover, I find that the fur is other fluorides which liberate freehydroflu- 75 carroted to a higher degree and that the oric acid areequivalents of the ammonium carroted fur has better felting qualities.fluoride which I specifically use. Although I am unable to explain theaction Having thus described my invention, what which takes place,nevertheless I believe that I claim is: x the hydrogen peroxide in thepresence-of the 1. A carroting solution comprising an nitric acid in thesolution, plays a substantial aqueous solution of. mercuric nitrate,hydroart in the carroting action itself and ungen peroxide, nitric acidand a soluble fluodoubtedly acts as a carroting agent as well as ridereactive with the nitric acid to form a bleach. Furthermore, the nitricacid in the hydrofluoric acid. solution tends to stabilize the hydrogen2. A carroting solution comprising an eroxide and prevent itsdecomposition and aqueous solution of mercuric nitrate, hydroby theco-joint action of the mercuric nitrate, gen peroxide, and nitric acidto which has the nitric acid and the hydrogen peroxide, been added asmall amount of a soluble fluam able to obtain a carroted fur which isreoride.

markably free from the yellow color cus- 3. A carroting solutioncomprising an tomarily resulting when mercuric nitrate is aqueoussolution of mercuric nitrate, hydroused alone. It may be that thehydrogen gen peroxide and nitric acid to which has peroxide in additionto its carroting and been added a small quantity of ammonium bleachingaction, restrains the normal action fluoride.

of the free nitric acid on the protein constitu- 4:. A carrotingsolution comprising an cuts of the fur fiber since it is an observedaqueous solution of about one half gallono fact that nitric acid willdiscolor protein mercuric nitrate solution containing about material.thirty two percent of mercuric nitrate, and

Instead of ammonium fluoride, I can use twenty percent of nitric acid,one and one other soluble fluorides such as hydrofluoric half gallons ofwater containing about one acid and alkali metal fluorides. In mycomhalf ounce of ammonium fluoride, and two position, the fluoride, inaddition to acting as and one half gallons of hydrogen peroxide acleanser? to remove what is commonly solution, the whole being dilutedwith about termed rust, doubtless dissolves any silitwo and one halfgallons of water.

40 ceous material which may form a part of the 5. The process ofcarroting fur which comcoating about the fur fiber. Ammonium prisessubjecting the fur to the action of an fluoride or other solublefluoride, in the presaqueous carroting solution containing merence ofthe free nitric acid probably reacts curic nitrate, hydrogen peroxideand nitric to liberate free hydrofluoric acid and this in acid to whichhas been added a small amountturn attacks the siliceous material inmuchthe of a soluble fluoride.

same way that glass is etched by a hydro- 6. The process of carrotingfur which comfluoric acid solution. It is unlikely that the prisessubjecting the fur to the action of an acid attacks the waxy coatingwhich is assoaqueous carroting solution containing merr ciated with thefibers since ordinary wax is curic nitrate, hydrogen peroxide, andnitric not dissolved by such an acid. More probaacid, to which has beenadded a small quanbly the fluoride dissolves a superficial coattity ofammonium fluoride. ing of siliceous material overlying the waxy CLARENCEL. WEIRICI'I.

coating itself and thus permits the actual

